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  2. Fermat's principle - Wikipedia

    en.wikipedia.org/wiki/Fermat's_principle

    Fermat's principle states that the path taken by a ray between two given points is the path that can be traveled in the least time. First proposed by the French mathematician Pierre de Fermat in 1662, as a means of explaining the ordinary law of refraction of light (Fig. 1), Fermat's principle was initially controversial because it seemed to ...

  3. Visual system - Wikipedia

    en.wikipedia.org/wiki/Visual_system

    The visual system is the physiological basis of visual perception (the ability to detect and process light).The system detects, transduces and interprets information concerning light within the visible range to construct an image and build a mental model of the surrounding environment.

  4. Optics - Wikipedia

    en.wikipedia.org/wiki/Optics

    Greek philosophy on optics broke down into two opposing theories on how vision worked, the intromission theory and the emission theory. [4] The intromission approach saw vision as coming from objects casting off copies of themselves (called eidola) that were captured by the eye.

  5. Geometrical optics - Wikipedia

    en.wikipedia.org/wiki/Geometrical_optics

    A light ray is a line or curve that is perpendicular to the light's wavefronts (and is therefore collinear with the wave vector). A slightly more rigorous definition of a light ray follows from Fermat's principle, which states that the path taken between two points by a ray of light is the path that can be traversed in the least time. [1]

  6. Foucault's measurements of the speed of light - Wikipedia

    en.wikipedia.org/wiki/Foucault's_measurements_of...

    Light from a passing through a slit (not shown) is reflected by mirror m (rotating clockwise around c) towards the concave spherical mirrors M and M'. Lens L forms images of the slit on the surfaces of the two concave mirrors. The light path from m to M is entirely through air, while the light path from m to M' is mostly through a water-filled ...

  7. Line of sight - Wikipedia

    en.wikipedia.org/wiki/Line_of_sight

    The term "line" typically presumes that the light by which the observed object is seen travels as a straight ray, which is sometimes not the case as light can take a curved/angulated path when reflected from a mirror, [5] refracted by a lens or density changes in the traversed media, or deflected by a gravitational field. Fields of study ...

  8. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    However, these jets are not moving at speeds in excess of the speed of light: the apparent superluminal motion is a projection effect caused by objects moving near the speed of light and approaching Earth at a small angle to the line of sight: since the light which was emitted when the jet was farther away took longer to reach the Earth, the ...

  9. Visual perception - Wikipedia

    en.wikipedia.org/wiki/Visual_perception

    Recent descriptions of visual association cortex describe a division into two functional pathways, a ventral and a dorsal pathway. This conjecture is known as the two streams hypothesis . The human visual system is generally believed to be sensitive to visible light in the range of wavelengths between 370 and 730 nanometers of the ...